1. Field of the Invention
The present invention relates to a transportation wheel for a treadmill, and more particularly to a transportation wheel having an engraved pattern on a roller where the pattern is similar to a pattern on the inner surface of the traveling belt. Because of the similar patterns, the transportation wheel is able to drive the traveling belt efficiently.
2. Description of Related Art
With reference to FIG. 4, a treadmill (40) has a front end and a rear end and comprises a transportation wheel (41), a freely-rotating wheel (not numbered) and a traveling belt (42). The transportation wheel (41) mounted at the front end of the treadmill (40). The freely-rotating wheel is mounted at the rear end of the treadmill (40) The traveling belt (42) is mounted around the transportation wheel (41) and the freely-rotating wheel.
The transportation wheel (41) is adapted to drive the traveling belt (42) at the same speed as the transportation wheel (41). The transportation wheel (41) comprises a roller (43), which adapts to attach a drive assembly (44) on one end of the roller (43). The roller (43) has two slightly tapered ends, an enlarged middle portion and two engraved helix patterns (45) defined on the middle portion of the outer periphery of the roller (43), wherein the engraved helix patterns are grooves and are formed in opposite directions to be a symmetrical configuration. When a user steps on the treadmill, most of the force is applied to the enlarged middle portion of the roller (43), which makes the traveling belt (42) press the middle portion tighter than the tapered ends of the roller (43). Thus, no side-force is applied to the traveling belt (42), and the traveling belt (42) is not easily detached from the roller (43). Additionally, the engraved helix patterns (45) evenly disperse the forces generated by and applied to the moving traveling belt (42) and keep the traveling belt (42) in the middle portion of the roller (43) even when the roller (43) is rotating.
However, the traveling belt (42) has an inner surface that is made of fabric and has a texture different from the engraved helix patterns (45) on the roller (43). Therefore, the roller (43) cannot provide sufficient friction to drive the traveling belt (42).
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional transportation wheel.